Plus, don't miss
our first day report where we
talk Hammer, memory, performance initiatives and the inexpensive nVidia nForce
415-D.

===================================

HyperTransport

High-speed interconnects in general and HyperTransport in
particular were popular subjects at Platform Conference. Over ten seminars
were dedicated to HyperTransport during the two day event, a strong sign that
this technology is rapidly taking off to becoming an accepted industry standard.

We have discussed HyperTransport in some detail in
previous
articles. To recount some of the highlights, HyperTransport greatly
boosts interconnect bandwidths while reducing latencies and pin counts.
The technology is flexible so that it can be scaled to different link widths
according to bandwidth demands and pin count requirements. The chart below
shows the pin counts for the various link width options.

HyperTransport pin counts versus link width

Not only are link widths customizable, but the
interlink frequency can also be varied. Shown in the chart below,
bandwidth can be scaled from 200 MB/s (PCI bandwidth is something less than
133MB/s) to 12.8 GB/s and higher throughput has been obtained in the lab.

HyperTransport bandwidth versus pin count and frequency

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Topology

Several new topological HyperTransport
features were detailed. In addition to "Tunnel devices" where a component
resides on the HyperTransport bus and passes the signal onto additional devices
down the HT chain, so-called "Caves," "Bridges" and combination devices were
outlined.

Caves are dead-end peripherals. Bridges are
Cave devices that also containing HyperTransport host controllers. The
graph below shows a few ways to chain together these HT-enabled devices.

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Box-to-Box Interconnect

Intel's new archnemesis, Broadcom, was
showing off HyperTransport being used successfully as a box-to-box interconnect,
likely foreshadowing future applications for this flexible technology.

Broadcom has linked two of its MIPS-based BCM1250 platforms using
HyperTransport

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NOTE:
Since this article contains many images, we are breaking it up into several
pages for the convenience of our readers with low bandwidth connections.